Diagnosis/troubleshooting PSM 5.7

DIAGNOSIS/TROUBLESHOOTING PSM 5.7 (FAULT CODE 4216)

Work instruction			Display OK	If not OK
1	Visual inspection	Examine speed sensor and lead at the rear left for external damage Check speed sensor plug for corrosion	Step 2	Repair speed sensor and lead Repair speed sensor plug ->End
2	Check speed sensors	Ignition off Disconnect plug from speed sensor Measure resistance between pin 1 and pin 2 on speed sensor	1 k to 3 k Step 3	>3k or< 1 k Step 9
3	Check function of speed sensor	Ignition off Set AC measuring range on the multimeter Jack the vehicle up and turn the rear left wheel by hand Measure voltage between pin 4 and pin 5 of speed sensor	Measureable AC voltage, approx. same level as to speed sensor of an opposite wheel at same wheel speed Step 5	No AC voltage measureable Step 5
4	Mechanical function	Check speed sensor and toothed ring at the rear left for soiling and external damage	Step 9	Clean toothed ring and replace, if necessary ->End
5	Check leads of speed sensor for short circuit to B+	Ignition off Pull plug off the PSM control unit Ignition on Measure voltage between PSM control unit plug pin 29 and ground Measure voltage between PSM control unit plug pin 14 and ground	< 0.3V Step 6	Short circuit to B+ between PSM control unit plug pin 29 or pin 14 and speed sensor pin 4 or pin 5 Repair wiring harness ->End
6	Check leads of speed sensor for short circuit to ground	Ignition off Measure resistance between PSM control unit plug pin 29 and ground Measure resistance between PSM control unit plug pin 14 and ground	Step 7	Short circuit to ground between PSM control unit plug pin 29 or pin 14 and speed sensor pin 4 or pin 5 Repair wiring harness ->End
7	Check leads of speed sensor for open circuit	Ignition off Measure resistance between PSM control unit plug pin 29 and pin 4 on speed sensor Measure resistance between PSM control unit plug pin 14 and pin 5 on speed sensor	0 Step 8	Open circuit in leads of speed sensor Repair wiring harness ->End
8	Check leads of speed sensor for short circuit with respect to each other	Ignition off Measure resistance between PSM control unit plug pin 29 and pin 14	Step 10	Open circuit in leads of speed sensor with respect to each other Repair wiring harness ->End
9	Replace rear left speed sensor		->End
10	Replace PSM control unit		->End